Distinct roles of the adaptor protein Shc and focal adhesion kinase in integrin signaling to ERK Journal Article

Authors: Barberis, L.; Wary, K. K.; Fiucci, G.; Liu, F.; Hirsch, E.; Brancaccio, M.; Altruda, F.; Tarone, G.; Giancotti, F. G.
Article Title: Distinct roles of the adaptor protein Shc and focal adhesion kinase in integrin signaling to ERK
Abstract: It has been proposed that integrins activate ERK through the adaptor protein Shc independently of focal adhesion kinase (FAK) or through FAK acting on multiple target effectors, including Shc. We show that disruption of the actin cytoskeleton by cytochalasin D causes a complete inhibition of FAK but does not inhibit Shc signaling and activation of ERK. We have then generated primary fibroblasts carrying a targeted deletion of the segment of β1 subunit cytoplasmic domain required for activation of FAK. Analysis of these cells indicates that FAK is not necessary for efficient tyrosine phosphorylation of Shc, association of Shc with Grb2, and activation of ERK in response to matrix adhesion. In addition, integrin-mediated activation of FAK does not appear to be required for signaling to ERK following growth factor stimulation. To examine if FAK could contribute to the activation of ERK in a cell type-specific manner through the Rap1/B-Raf pathway, we have used Swiss-3T3 cells, which in contrast to primary fibroblasts express B-Raf. Dominant negative studies indicate that Shc mediates the early phase and peak, whereas FAK, p130(CAS), Crk, and Rap1 contribute to the late phase of integrin-dependent activation of ERK in these cells. In addition, introduction of B-Raf enhances and sustains integrin-mediated activation of ERK in wild-type primary fibroblasts but not in those carrying the targeted deletion of the β1 cytoplasmic domain. Thus, the Shc and FAK pathways are activated independently and function in a parallel fashion. Although not necessary for signaling to ERK in primary fibroblasts, FAK may enhance and prolong integrin-mediated activation of ERK through p130(CAS), Crk, and Rap1 in cells expressing B-Raf.
Keywords: signal transduction; mitogen activated protein kinase; protein phosphorylation; human cell; gene deletion; proto-oncogene proteins; raf protein; nonhuman; protein domain; proteins; animal cell; animals; mice; enzyme inhibition; enzyme activation; animalia; fibroblasts; adaptor proteins, signal transducing; phosphoproteins; protein-tyrosine kinases; mitogen-activated protein kinases; enzyme subunit; focal adhesion kinase; integrin; retinoblastoma-like protein p130; integrins; 3t3 cells; crk-associated substrate protein; focal adhesion protein-tyrosine kinases; adaptor proteins, vesicular transport; protein shc; focal adhesion kinase 1; fibronectins; rap protein; cytochalasin d; human; priority journal; article; src homology domains; rap1 gtp-binding proteins; proto-oncogene proteins c-crk
Journal Title: Journal of Biological Chemistry
Volume: 275
Issue: 47
ISSN: 0021-9258
Publisher: American Society for Biochemistry and Molecular Biology  
Date Published: 2000-11-24
Start Page: 36532
End Page: 36540
Language: English
DOI: 10.1074/jbc.M002487200
PUBMED: 10976102
PROVIDER: scopus
Notes: Export Date: 18 November 2015 -- Source: Scopus
Citation Impact
MSK Authors
  1. Feng Liu
    2 Liu
  2. Giusy   Fiucci
    2 Fiucci
  3. Kishore K Wary
    8 Wary